In conventional data communications networks, devices called “switches” must store every media-access control (“MAC”) address of each source/destination in a network. For example, if the switches are central office (“CO”) node switches (“nodes” for short) each typically stores 20,000 MAC addresses. Further, associated HUB nodes may each store 60,000 MAC addresses (when 3 COs are aggregated) while associated Point-of Presence (“POP”) nodes may each store 120,000 MAC addresses (when 6 COs are aggregated). Thus, in a conventional network a large number of MAC addresses must be stored and maintained. These addresses are stored in so-called MAC address tables. The storage of such a large number of addresses and associated tables, however, has its disadvantages.
First, the storage of a large number of MAC address tables leads to long network convergence times, which in turn places limitations on how fast a network can grow. Second, in the event of a network failure the contents of these large MAC address tables must be “re-learned” causing so-called “broadcast storms”. Although, so called “MAC in MAC” techniques may mitigate some of the problems related to the storage of large MAC address tables at HUB nodes, problems still persist when it comes to CO and POP nodes.
In sum, it is desirable to reduce the number of MAC addresses and tables that need to be stored by nodes in a network. It is believed that a reduction will have a significant impact on how large a network can become (i.e., greater scalability) which in turn may directly affect the cost of operating, maintaining and upgrading a network.